Noted, i checked the boss code and everythig seemed normal, and i playtested again on both Firefox and Chrome and i was able to go through the full game with no crash, sorry about the inconvenience, but here i heve no clue what could have happened here to cause a crash on your end :/
The asteroids could be a nice feature post jam if i get some time, thanks for the suggestion :)
The enemies mostly have the same color cause i wanted them to feel like they were part of a similar uniform alien force, but i guess they do look a bit too samey that way, so i(ll take note if i can post jam this i'll add some more variety in the color schemes.
The speed issue has been noted as many peolpe pointed it out as well so if i can post jam then again i'll change this for sure to have the pace up a bit.
Concerning player ships : You can change your ship after death, i just didn't convey it all that well cause i made the continue Ui a bit too minimal, but if you've noticed, next to the continue you see "Ship 01,02,etc.. your current ship" and tha character hud portrait, you can use the direction key when this menu pop up to select any of the 5 ships just like in the old arcade games. But i don't blame anyone if they didn't catch that as i didn't conveyed it all that well and explained it nowhere on the page's controls section ^^'
Thanks again for the additional feedback, have a good one dude :)